The present invention relates to an optical information processor such as a digital optical disc, and more particularly to an optical information processor which can prevent data from being destroyed due to the digression of a light spot from a track.
In a digital optical disc, the digression of a light spot from a track being traced causes serious consequences, as compared with similar digression in a conventional commercial optical disc (that is, an optical video disc or a PCM audio disc). When the tracking error occurs in a recording period, not only data to be recorded is lost, but also previously recorded data is destroyed since the former is erroneously superposed on the latter. In order to prevent such troubles, it is very important to detect a tracking error with high reliability.